Low-power start-up and direction control circuitry for an irrigation system

ABSTRACT

An electric circuit for remotely starting and controlling the direction of a center pivot irrigation system comprises a first transformer, a second transformer, a first relay, a second relay, a third relay, and a fourth relay. The first transformer is coupled to a voltage source with a first voltage and may step the first voltage down to a second voltage. The second transformer is coupled to the first transformer, receiving a third voltage and stepping the third voltage up to a fourth voltage. The first relay may include contacts that are open when the irrigation system is started remotely. The second relay may include contacts that are closed when the irrigation system is started remotely. The third relay may include contacts that are closed momentarily to drive the system in a first direction. The fourth relay may include contacts that are closed momentarily to drive the system in a second direction.

RELATED APPLICATIONS

This non-provisional patent application claims priority benefit withregard to all common subject matter of the earlier filed U.S.Provisional Patent Application titled “LOW-POWER START-UP FOR IRRIGATIONSYSTEM AND DIRECTION MONITOR AND CONTROL FOR IRRIGATION SYSTEM”, Ser.No. 61/353,012, filed on Jun. 9, 2010, which is hereby incorporated byreference in its entirety into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to electric circuitry foruse with a center pivot irrigation system. More particularly,embodiments of the present invention relate to electric circuits forstarting a center pivot irrigation system from a remote location.

2. Description of the Related Art

Center pivot irrigation systems are used for crop irrigation andgenerally include components that require electric power to operate. Thesystems may be started and stopped remotely by a user with a wirelessdevice. The systems may include wiring for starting the system remotelythat is energized at dangerous levels of voltage even when theirrigation system is not operating.

SUMMARY OF THE INVENTION

Embodiments of the present invention solve the above-mentioned problemsand provide a distinct advance in the art of electric circuitry for usewith a center pivot irrigation system. More particularly, embodiments ofthe invention provide electric circuits for starting and controlling thedirection of a center pivot irrigation system from a remote locationthat include low power wiring that extends the length of the irrigationsystem.

One embodiment of the invention is an electric circuit for remotelystarting and controlling the direction of a center pivot irrigationsystem and comprising a first transformer, a second transformer, a firstrelay, a second relay, a third relay, and a fourth relay. The firsttransformer may include a primary side coupled to a first voltage sourcewith a first voltage and a secondary side presenting a second voltage.The first transformer may be configured to step the first voltage downto a lower second voltage. The second transformer may include a primaryside coupled to the secondary side of the first transformer with a thirdvoltage and a secondary side presenting a fourth voltage. The secondtransformer may be configured to step the third voltage up to a higherfourth voltage.

The first relay may include a first input, a first contact, and a secondcontact. The first input may change a connection between the first andsecond contacts, wherein the connection between the first and secondcontacts is open when the center pivot irrigation system is startedremotely. The second relay may include a second input, a third contactconnected to the second contact, and a fourth contact. The second inputmay change a connection between the third and fourth contacts, whereinthe connection between the third and fourth contacts is closed when thecenter pivot irrigation system is started remotely. The fourth contactmay be connected to the secondary side of the second transformer and mayreceive the fourth voltage. The first contact may be connected to afirst cable that receives no voltage when the center pivot irrigationsystem is started remotely. The third contact may be connected to asecond cable that receives the fourth voltage when the center pivotirrigation system is started remotely.

The third relay may include a third input, a fifth contact, and a sixthcontact connected to the first contact. The third input may change aconnection between the fifth and sixth contacts, wherein the connectionbetween the fifth and sixth contacts is closed momentarily to drive thecenter pivot irrigation system in a first direction. The fourth relaymay include a fourth input, a seventh contact, and an eighth contactconnected to the first contact. The fourth input may change a connectionbetween the seventh and eighth contacts, wherein the connection betweenthe seventh and eighth contacts is closed momentarily to drive thecenter pivot irrigation system in a second direction.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a block schematic diagram of an electric circuit for remotelystarting and controlling the direction of a center pivot irrigationsystem, constructed in accordance with various embodiments of thecurrent invention; and

FIG. 2 is a perspective view of a central pivot irrigation systemconstructed in accordance with embodiments of the invention.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

An electric circuit 10 for remotely starting and controlling thedirection of an irrigation system 100, constructed in accordance with afirst embodiment of the present invention, is shown in FIG. 1 andbroadly comprises a first transformer 12, a second transformer 14, afirst relay 16, a second relay 18, a third relay 20, a fourth relay 22,and a monitor circuit 24.

Turning to FIG. 2, an exemplary irrigation system 100 on whichprinciples of the present invention may be implemented is illustrated.An embodiment of the irrigation system 100 is a central pivot irrigationsystem and broadly comprises a fixed central pivot 112 and a mainsection 114 pivotally connected to the central pivot. The irrigationsystem 100 may also comprise an extension arm (also commonly referred toas a “swing arm” or “corner arm”) pivotally connected to the free end ofthe main section.

The fixed central pivot 112 may be a tower 116 or any other supportstructure about which the main section 114 may pivot. The central pivothas access to a well, water tank, or other source of water and may alsobe coupled with a tank or other source of agricultural products toinject fertilizers, pesticides and/or other chemicals into the water forapplication during irrigation.

The main section 114 may comprise any number of mobile support towers116A-D, the outermost 116D of which is referred to herein as an “endtower”. The support towers are connected to the fixed central pivot 112and to one another by truss sections 118A-D or other supports to form anumber of interconnected spans.

The mobile towers have wheels 120A-D, at least one of which is driven bysuitable drive motors 122A-D. Each motor 122A-D turns at least one ofits wheels 120A-D through a drive shaft to move its mobile tower andthus the main section in a circle about the central pivot to irrigate afield. The motors 122A-D may include integral or external relays so theymay be turned on, off, and reversed as described below. The motors mayalso have several speeds or be equipped with variable speed drives.

Although not required, some or all of the towers 116A-D may be equippedwith steerable wheels pivoted about upright axes by suitable steeringmotors so that the towers can follow a predetermined track. U.S. Pat.No. 4,508,269 in the name of Davis et al. is hereby incorporated byreference in its entirety into the present specification for adisclosure of ground drive motors and steering motors associated with anirrigation machine. As is also well known, the drive motors for thetowers are controlled by a suitable safety system such that they may beslowed or completely shut down in the event of the detection of anadverse circumstance, all of which is disclosed, for example, in U.S.Pat. No. 6,042,031 to Christensen, et al. incorporated herein byreference in its entirety.

Each of the truss sections 118A-D carries or otherwise supports aconduit section 124A-D or other fluid distribution mechanism that isconnected in fluid communication with all other conduit sections. Aplurality of sprinkler heads, spray guns, drop nozzles, or otherfluid-emitting devices are spaced along the conduit sections 124A-D toapply water and/or other fluids to land underneath the irrigationsystem.

The irrigation system 100 may also include an optional extension arm(not shown) pivotally connected to the end tower and may be supported bya swing tower with steerable wheels driven by a motor. The extension armmay be joined to the end tower by an articulating pivot joint. Theextension arm is folded in relative to the end tower when it is notirrigating a corner of a field and may be pivoted outwardly away fromthe end tower while irrigating the corners of a field.

The irrigation system 100 may also include one or more high pressuresprayers or end guns 126 mounted to the end tower 116D or to the end ofthe extension arm. The end guns are activated at the corners of a fieldor other designated areas to increase the amount of land that can beirrigated.

The irrigation system 100 illustrated in FIG. 2 has four mobile supporttowers; however, it may comprise any number of mobile support towers,truss sections, wheels, and drive motors without departing from thescope of the present invention.

The irrigation system 100 may also include a main control system forcontrolling movement of the mobile towers 116A-D and operation of thefluid-emitting devices in accordance with an irrigation design program.The main control system may include a processor or other computingdevice with inputs that receive positional information from one or moreGPS receivers mounted to the end tower or elsewhere. The processor mayalternatively receive position information from angle encoders mountedbetween the central pivot and a first span of the main section. Theprocessor may also include outputs connected to relay-controlled valvesconnected to the water-emitting devices and relay-controlled electricmotors connected to the drive wheels of the mobile towers.

The irrigation system 100 may also include other components with whichthe electric circuit 10 interacts to remotely start and control thedirection of the system. The other components, shown in FIG. 1, mayinclude a main control panel 26, a span mounted panel 28, a first line30, a second line 32, a third line 34, a fourth line 36, a timer 38, andat least one safety switch 40.

The main control panel 26 may be an enclosed panel box that is typicallymounted at or near the central pivot 112 and may include an electricalpower source or at least access to an electric power source. The maincontrol panel may further include the main control system discussedabove. The electric power source may supply alternating current (AC) ordirect current (DC) voltage, as is known in the art. An exemplaryelectric power source may supply approximately 120 volts (V) AC.

The span mounted panel 28 may be an enclosed panel box that is typicallymounted at or near the tower 116D at the end of the span. The spanmounted panel 28 may house the first relay 16, the second relay 18, thethird relay 20, and the fourth relay. In various embodiments, the spanmounted panel 28 may also house the timer 38 and the second transformer14.

The first line 30, labeled “Safety Out” in FIG. 1, the second line 32,labeled “Safety Return”, the third line 34, labeled “Forward Control”,and the fourth line, labeled “Reverse Control”, may each include anelectric current carrying metallic conductor such as a wire or cable.

The timer 38 may include digital or analog electric circuitry ormechanical components that are capable of keeping track of time andindicating when a certain period has expired. The timer 38 may also beprogrammable either locally at the timer 38 or wirelessly from a remotelocation. Accordingly, the timer 38 may also include wireless radiofrequency (RF) receiving circuitry. The timer 38 may further include anelectrical first contact 42 and an electrical second contact 44, suchthat the connection between the contacts 42, 44 is either opened orclosed at the end of the given time period. An exemplary timer 38 may beprogrammed for a certain period of irrigation or watering such thatduring the period of watering, the connection between the contacts 42,44 is closed. At the end of the watering period, the connection betweenthe contacts 42, 44 is opened. The timer 38 may be positioned in or nearthe span mounted panel 28.

The safety switch 40 may be mounted on a tower 116 and may include afirst contact 46 and a second contact 48. The safety switch 40 may haveelectrical or mechanical components that either close the connectionbetween the contacts 46, 48 or open the connection. An exemplary safetyswitch 40 may include monitors that monitor the safety conditions of thetower 116, such as whether the tower 116 is tilting or leaning. Thesafety switch 40 may be normally closed, but may open if any of thesafety conditions is not met.

The first transformer 12 may include electrical transforming componentsas are known in the art, such as at least two inductively coupled coilswith a certain winding ratio between the coils. The first transformer 12may include a primary 43 side operating at a primary voltage and asecondary 45 side operating at a secondary voltage. If the primaryvoltage is greater than the secondary voltage, then the firsttransformer 12 is a step-down transformer. If the primary voltage isless than the secondary voltage, then the first transformer 12 is astep-up transformer. An exemplary first transformer 12 is a step-downtransformer with a primary voltage of approximately 120 VAC and asecondary voltage of approximately 28 VAC. The first transformer 12 maybe positioned in or near the main control panel 26.

The second transformer 14 may be similar to the first transformer 12 andmay include a primary 47 and a secondary 49. The primary 47 of thesecond transformer 14 is electrically connected to the secondary 45 ofthe first transformer 12. The second transformer 14 ideally should be amirror image of the first transformer 12, with a primary voltage tomatch the secondary voltage of the first transformer 12 and a secondaryvoltage to match the primary voltage of the first transformer 12. Inactual implementation, the second transformer 14 may be located at alarge distance (approximately 0.25 miles) from the first transformer 12with wiring making the connection therebetween. There may be a voltagedrop across the wires, such that the voltage at the primary 47 of thesecond transformer 14 is less than the voltage at the secondary 45 ofthe first transformer 12. Thus, in some embodiments, the secondtransformer 14 may have a different winding ratio from the firsttransformer 12 in order to account for the voltage drop across theconnecting wires. An exemplary second transformer 14 may be a step-uptransformer with a primary voltage of approximately 24 VAC and asecondary voltage of approximately 120 VAC. The second transformer 14may be positioned in or near the span mounted panel 28.

The first relay 16 may include an input 50 and a first contact 52 and asecond contact 54. In various embodiments, the relay may be anelectromagnetic type with an input that includes a coil. The first relay16 may operate in at least two modes. In the first mode, when the input50 is not energized, the connection between the contacts 52, 54 isclosed. When the input 50 is energized, the connection between thecontacts 52, 54 is opened. In the second mode, when the input 50 is notenergized, the connection between the contacts 52, 54 is open. When theinput 50 is energized, the connection between the contacts 52, 54 isclosed. An exemplary first relay 16 may include a wireless receivercircuit coupled to the input 50 such that the input 50 may be energizedand de-energized remotely by a user, such as the owner or manager of theirrigation system 100. The user may send a first relay signal to thefirst relay 16 from an electronic device with wireless transmissioncapabilities such as a cell phone, a tablet computer, a laptop computer,a desktop computer, or the like. Thus, the user may control theoperation of the first relay 16 by sending the first relay signal toeither open the contacts 52, 54 or open the contacts 52, 54.

The second relay 18 may be substantially similar to the first relay 16and may include an input 56 and a first contact 58 and a second contact60. The input 56 of the second relay 18 may also be coupled to awireless receiver circuit such that the input 56 may be energized andde-energized remotely by a user. Thus, the user may either open thecontacts 58, 60 or close the contacts 58, 60 by transmitting a secondrelay signal remotely.

The third relay 20 may be substantially similar to the first relay 16and may include an input 62 and a first contact 64 and a second contact66. The input 62 of the third relay 20 may also be coupled to a wirelessreceiver circuit such that the input 62 may be energized andde-energized remotely by a user. Thus, the user may either open thecontacts 64, 66 or close the contacts 64, 66 by transmitting a thirdrelay signal remotely. In various embodiments, the contacts 64, 66 ofthe third relay 20 may be normally open and may close momentarily whenthe third relay signal is received.

The fourth relay 22 may be substantially similar to the first relay 16and may include an input 68 and a first contact 70 and a second contact72. The input 68 of the fourth relay 22 may also be coupled to awireless receiver circuit such that the input 68 may be energized andde-energized remotely by a user. Thus, the user may either open thecontacts 70, 72 or close the contacts 70, 72 by transmitting a fourthrelay signal remotely. In various embodiments, the contacts 70, 72 ofthe fourth relay 22 may be normally open and may close momentarily whenthe fourth relay signal is received.

The monitor circuit 24 may include analog and or digital circuitry thatcan sense a voltage, determine the value of the voltage, and generate aready signal if the value of the voltage is at or above a predeterminedlevel. The monitor circuit 24 may also include wireless transmissioncircuitry to transmit the ready signal to a remote user.

Referring to FIG. 1, the irrigation system 100 may also include a safetyloop 76 formed by the first line 30, the timer 38, the first relay 16,the safety switches 40, and the second line 32, described in more detailas follows. The first line 30 is connected to the main control panel 26and the first and second contacts 42, 44 of the timer 38. The first line30 is also connected to the first contact 52 of the first relay 16. Thesecond contact 54 of the first relay 16 is connected to the second line32, which in turn is connected to both contacts 46, 48 of the safetyswitch 40 and to the main control panel 26. In embodiments where thereare a plurality of safety switches 40, the second line 32 is connectedto both contacts 46, 48 of all the safety switches 40. The primary 43 ofthe first transformer 12 is connected to a control voltage from the maincontrol panel 26. The secondary of the first transformer 12 is connectedto the primary 47 of the second transformer 14. The secondary 49 of thesecond transformer 14 is connected to the second contact 60 of thesecond relay 18. The first contact 58 of the second relay 18 isconnected to the second contact 54 of the first relay 16. As mentionedabove, the inputs 50, 56 of the first relay 16 and the second relay 18may be coupled to a wireless receiver such that the first relay 16 andthe second relay 18 can be controlled remotely.

The first line 30 is also connected to the input 74 of the monitorcircuit 24, the second contact 66 of the third relay 20 and the secondcontact 72 of the fourth relay 22. The first contact 64 of the thirdrelay 20 is connected to the third line 34, which is also connected tothe main control panel 26. The first contact 70 of the fourth relay 22is connected to fourth line 36, which is also connected to the maincontrol panel 26. As discussed above, the inputs 62, 68 of the thirdrelay 20 and the fourth relay 22 may be coupled to a wireless receiversuch that the third relay 20 and the fourth relay 22 can be controlledremotely.

The irrigation system 100 may be started either locally or remotely. Tostart the system locally, a user generally pushes a button (not shown inFIG. 1) that supplies electric power to the irrigation components. Whilethe button is pushed, the safety loop is bypassed and is not active.Once the system is operating, the button is released. Alternatively, thebutton may be released after a certain time period. When the button isreleased, a first voltage is applied to the first line 30 at the maincontrol panel 26. Typically, the first voltage is approximately 120 VAC.Under normal irrigation conditions, the contacts 42, 44 of the timer 38are closed, the contacts 52, 54 of the first relay 16 are closed, thecontacts 58, 60 of the second relay 18 are open, and the contacts 46, 48of the safety switches 40 are closed. The safety loop 76 is closed.Thus, the first voltage is present on the second line 32 at the maincontrol panel 26, which allows electrical power to continue to bedelivered to the irrigation components requiring power.

A user may wish to halt watering and may send the first relay signal tothe first relay 16 to open the contacts 52, 54. The opening of thecontacts 52, 54 breaks the safety loop 76 and the irrigation componentsrequiring electric power cease to receive the power and the irrigationsystem 100 stops. The system may also be restarted by the user remotely.

To start the irrigation system 100 remotely, a remote start process maybe followed such that the contacts 52, 54 of the first relay 16 areopened, and the contacts 58, 60 of the second relay 18 are closed. Atthe main control panel 26, a second voltage (the control voltage) isapplied to the primary 43 of the first transformer 12. An exemplarysecond voltage is approximately 120 VAC. A third voltage is present onthe secondary 45 of the first transformer 12. Due to the parameters ofthe windings of the first transformer 12, the third voltage isapproximately 28 VAC. A fourth voltage is present on the primary 47 ofthe second transformer 14. If the second transformer 14 is located closeto the first transformer 12 and the cables between the two are short,then the fourth voltage may be approximately the same as the thirdvoltage. However, typically, the first transformer 12 is at the centralpivot 112 and the second transformer 14 is at the last tower 116D of theirrigation span. Thus, the cables are long and as a result, the fourthvoltage is less than the third voltage due to the voltage drop of thecables. An exemplary fourth voltage is approximately 24 VAC. A fifthvoltage is present on the secondary 49 of the second transformer 14. Dueto the parameters of the windings of the second transformer 14, thefifth voltage is approximately 120 VAC. Therefore, by design, the fifthvoltage is approximately the same as the second voltage or the controlvoltage from the main control panel 26. The fifth voltage is applied tothe second relay 18 and in turn, to the second line 32. Applying avoltage, such as the control voltage, to the second line 32 provideselectric power to the irrigation system 100, which then starts theprocess of irrigation. When the system starts, the contacts 52, 54 ofthe first relay 16 are closed and the contacts 58, 60 of the secondrelay 18 are opened. During the beginning of the remote start process,the contacts 52, 54 of the first relay 16 are opened in order to avoidputting a voltage on the first line 30, which is connected to the maincontrol panel 26 and might draw more current than the second transformer14 can supply.

In various embodiments, the remote start process may be automated, suchthat the first relay signal is sent to the first relay 16 to open thecontacts 52, 54. The second relay signal is sent to the second relay 18to close the contacts 58, 60. After a period of time has passed to allowthe irrigation system 100 components to start, the first signal is sentto the first relay 16 to close the contacts 52, 54, and the second relaysignal is sent to the second relay 18 to open the contacts 58, 60.

Once the irrigation system 100 is started, the direction of travel forthe span may be selected. Forward may be considered counterclockwisewhen the irrigation system 100 is viewed from above. Reverse may beconsidered clockwise when viewed from above. The monitor circuit 24monitors the voltage of the first line 30 and generates the ready signalwhen the voltage is at or above a certain level. Typically, that levelis approximately 120 VAC. When the ready signal is received by the user,the direction of travel may be selected by sending the third relaysignal to the third relay 20 for the forward direction or the fourthrelay signal to the fourth relay 22 for the reverse direction. When thethird relay signal is received by the third relay 20, the contacts 64,66 may close momentarily to send a forward signal to the components thatdetermine the direction of the irrigation system 100. When the fourthrelay signal is received by the fourth relay 22, the contacts 70, 72 mayclose momentarily to send a reverse signal to the components thatdetermine the direction of the irrigation system 100.

In various embodiments, the monitor circuit 24 may be optional. In suchembodiments, the user or an automated processing system may wait a shortperiod of time, perhaps a few seconds, after the irrigation system 100starts before sending either the third relay signal or the fourth relaysignal.

The circuit 10 of the present invention provides the ability for airrigation system 100 to be started and have the direction chosenremotely, while also providing cables that extend the length of theirrigation span which are powered at a lower and safer voltage than thecontrol voltage from the main control panel 26. The first transformer12, positioned near the central pivot 112, steps the control voltagedown to a safer value (approximately 28 VAC, for example), and thesecond transformer 14, positioned near the end of the span, steps thevoltage up to the control voltage level. The control voltage(approximately 120 VAC) is required at the span mounted panel 28 forstarting the irrigation system 100 when the system is off. However,having cables along the span that are energized with a voltage might beunexpected when the irrigation system 100 is not running. Therefore,this setup provides a safer environment for a technician, or the like,to work since the voltage applied to the cables is at a safer value.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters patent includesthe following:

1. An electric circuit for remotely starting a center pivot irrigation system, the electric circuit comprising: a first transformer including a primary side coupled to a first voltage source with a first voltage and a secondary side presenting a second voltage, the first transformer configured such that the first voltage is greater than the second voltage; a second transformer including a primary side coupled to the secondary side of the first transformer with a third voltage and a secondary side presenting a fourth voltage, the second transformer configured such that the third voltage is less than the fourth voltage; a first relay including a first input, a first contact, and a second contact, the first input operable to change a connection between the first and second contacts, wherein the connection between the first and second contacts is open when the center pivot irrigation system is started remotely; and a second relay including a second input, a third contact connected to the second contact, and a fourth contact, the second input operable to change a connection between the third and fourth contacts, wherein the connection between the third and fourth contacts is closed when the center pivot irrigation system is started remotely.
 2. The electric circuit of claim 1, wherein the fourth contact is connected to the secondary side of the second transformer and receives the fourth voltage.
 3. The electric circuit of claim 2, wherein the first contact is connected to a first cable that receives no voltage when the center pivot irrigation system is started remotely.
 4. The electric circuit of claim 2, wherein the third contact is connected to a second cable that receives the fourth voltage when the center pivot irrigation system is started remotely.
 5. The electric circuit of claim 1, wherein the connection between the first and second contacts is closed when the center pivot irrigation system is irrigating.
 6. The electric circuit of claim 1, wherein the connection between the third and fourth contacts is open when the center pivot irrigation system is irrigating.
 7. The electric circuit of claim 1, wherein the first input is further operable to receive a remote wireless signal to change the connection between the first and second contacts.
 8. The electric circuit of claim 1, wherein the second input is further operable to receive a remote wireless signal to change the connection between the third and fourth contacts.
 9. The electric circuit of claim 1, wherein the first voltage is approximately 120 Volts AC, the second voltage is approximately 28 Volts AC, the third voltage is approximately 24 Volts AC, and the fourth voltage is approximately 120 Volts AC.
 10. An electric circuit for remotely starting and controlling the direction of a center pivot irrigation system, the electric circuit comprising: a first transformer including a primary side coupled to a first voltage source with a first voltage and a secondary side presenting a second voltage, the first transformer configured such that the first voltage is greater than the second voltage; a second transformer including a primary side coupled to the secondary side of the first transformer with a third voltage and a secondary side presenting a fourth voltage, the second transformer configured such that the third voltage is less than the fourth voltage; a first relay including a first input, a first contact, and a second contact, the first input operable to change a connection between the first and second contacts, wherein the connection between the first and second contacts is open when the center pivot irrigation system is started remotely; a second relay including a second input, a third contact connected to the second contact, and a fourth contact, the second input operable to change a connection between the third and fourth contacts, wherein the connection between the third and fourth contacts is closed when the center pivot irrigation system is started remotely; and a third relay including a third input, a fifth contact, and a sixth contact connected to the first contact, the third input operable to change a connection between the fifth and sixth contacts, wherein the connection between the fifth and sixth contacts is closed momentarily to drive the center pivot irrigation system in a first direction; and a fourth relay including a fourth input, a seventh contact, and an eighth contact connected to the first contact, the fourth input operable to change a connection between the seventh and eighth contacts, wherein the connection between the seventh and eighth contacts is closed momentarily to drive the center pivot irrigation system in a second direction.
 11. The electric circuit of claim 10, wherein the first contact is connected to a first cable presenting a fifth voltage and the fifth contact receives the fifth voltage when the connection between the fifth and sixth contacts is closed momentarily.
 12. The electric circuit of claim 10, wherein the first contact is connected to a first cable presenting a fifth voltage and the seventh contact receives the fifth voltage when the connection between the seventh and eighth contacts is closed momentarily.
 13. The electric circuit of claim 10, wherein the fourth contact is connected to the secondary side of the second transformer and receives the fourth voltage.
 14. The electric circuit of claim 13, wherein the first contact is connected to a first cable that receives no voltage when the center pivot irrigation system is started remotely.
 15. The electric circuit of claim 13, wherein the third contact is connected to a second cable that receives the fourth voltage when the center pivot irrigation system is started remotely.
 16. The electric circuit of claim 10, wherein the connection between the first and second contacts is closed and the connection between the third and fourth contacts is open when the center pivot irrigation system is irrigating.
 17. The electric circuit of claim 10, wherein the first input is further operable to receive a remote wireless signal to change the connection between the first and second contacts.
 18. The electric circuit of claim 10, wherein the second input is further operable to receive a remote wireless signal to change the connection between the third and fourth contacts.
 19. The electric circuit of claim 10, wherein the third input is further operable to receive a remote wireless signal to change the connection between the fifth and sixth contacts.
 20. The electric circuit of claim 10, wherein the fourth input is further operable to receive a remote wireless signal to change the connection between the seventh and eighth contacts. 